Interlayer for laminated glass, laminated glass, production method for embossing roll, and production method for interlayer for laminated glass

ABSTRACT

The present invention aims to provide an interlayer film for a laminated glass having recesses in the shape of engraved lines on both surfaces to exhibit excellent deaeration properties in production of a laminated glass and suppressing formation of a moire pattern when unwound from a rolled body thereof. The present invention also aims to provide a laminated glass including the interlayer film for a laminated glass, a method for producing an embossing roll suitably used for production of the interlayer film for a laminated glass, and a method for producing the interlayer film for a laminated glass. The present invention relates to an interlayer film for a laminated glass, having a large number of recesses on both surfaces, the recesses each having a groove shape with a continuous bottom and being regularly adjacent and parallel to each other, the interlayer film having a glossiness on a surface with the large number of recesses measured in conformity with JIS Z 8741-1997 of higher than 3% or a haze value measured in conformity with JIS K 7105-1981 of 87% or lower.

TECHNICAL FIELD

The present invention relates to an interlayer film for a laminatedglass having recesses in the shape of engraved lines on both surfaces toexhibit excellent deaeration properties in production of a laminatedglass and suppressing formation of a moire pattern when unwound from arolled body thereof. The present invention also relates to a laminatedglass including the interlayer film for a laminated glass, a method forproducing an embossing roll suitably used for production of theinterlayer film for a laminated glass, and a method for producing theinterlayer film for a laminated glass.

BACKGROUND ART

A laminated glass including two glass plates integrated through aninterlayer film for a laminated glass containing plasticized polyvinylbutyral is widely used, particularly, for vehicle windshields.

In the process for producing a laminated glass, deaeration propertiesupon stacking a glass plate and an interlayer film for a laminated glasson top of each other is important. The interlayer film for a laminatedglass therefore has fine protrusions and recesses formed on the surfacefor the purpose of ensuring the deaeration properties in production of alaminated glass. In particular, when the recesses each have a grooveshape with a continuous bottom and such recesses are regularly adjacentand parallel to each other (hereafter, also referred to as “recesses inthe shape of engraved lines”), remarkably excellent deaerationproperties can be exhibited.

In a method for producing a laminated glass, for example, an interlayerfilm for a laminated glass unwound from a rolled body is cut into anappropriate size, and the resulting interlayer film for a laminatedglass is sandwiched between at least two glass plates. The obtainedlaminate is placed in a rubber bag and vacuum suctioned so that theglass plates and the interlayer film are preliminarily pressure bondedwhile air remaining therebetween is removed. Then, the laminate ispressurized with heat, for example, in an autoclave for final pressurebonding (e.g., Patent Literature 1).

The interlayer film for a laminated glass having recesses in the shapeof engraved lines however suffers a streaky optical interference imagecalled a moire pattern when unwound from a rolled body thereof. Themoire pattern formed tires operator's eyes in the production process ofa laminated glass including alignment of glass plates and the interlayerfilm, leading to lower work efficiency.

A moire phenomenon is known to occur in the interlayer film for alaminated glass due to regularly arranged embosses on both surfaces ofthe interlayer film, and various means for preventing the moirephenomenon have been proposed (see Patent Literatures 2 and 3, forexample). A moire pattern that is formed when an interlayer film for alaminated glass having recesses in the shape of engraved lines isunwound from a rolled body thereof is however different incharacteristics from conventionally known moire phenomena. For example,it is not observed before the interlayer film is wound into a rolledbody and it disappears when heated. Such a moire pattern cannot beprevented by conventionally proposed means.

CITATION LIST Patent Literature

-   Patent Literature 1: JP H08-26789 A-   Patent Literature 2: JP 2000-7390 A-   Patent Literature 3: JP 2000-319045 A

SUMMARY OF INVENTION Technical Problem

The present invention aims to provide, in consideration of the state ofthe art, an interlayer film for a laminated glass having recesses in theshape of engraved lines on both surfaces to exhibit excellent deaerationproperties in production of a laminated glass and suppressing formationof a moire pattern when unwound from a rolled body thereof. The presentinvention also aims to provide a laminated glass including theinterlayer film for a laminated glass, a method for producing anembossing roll suitably used for production of the interlayer film for alaminated glass, and a method for producing the interlayer film for alaminated glass.

Solution to Problem

The present invention relates to an interlayer film for a laminatedglass, having a large number of recesses on both surfaces, the recesseseach having a groove shape with a continuous bottom and being regularlyadjacent and parallel to each other, the interlayer film having aglossiness on a surface with the large number of recesses measured inconformity with JIS Z 8741-1997 of higher than 3% or a haze valuemeasured in conformity with JIS K 7105-1981 of 87% or lower.

The present invention is specifically described in the following.

The present inventors studied about why an interlayer film for alaminated glass having recesses in the shape of engraved lines afterstorage as a rolled body suffers a moire pattern when unwound from therolled body.

The present inventors found out that the moire pattern is caused by acontact between protrusions corresponding to the recesses in the shapeof engraved lines when the interlayer film is wound into a rolled body.Specifically, when an interlayer film for a laminated glass havingrecesses in the shape of engraved lines on both surfaces is wound into arolled body, protrusions corresponding to the recesses in the shape ofengraved lines are made in contact with each other (FIG. 1(a)). Sincethe rolled body is stressed in the normal direction of the roll core dueto a tensile force upon rolling, contact points of the protrusions aredeformed. Namely, the shape of engraved lines on one surface of theinterlayer film for a laminated glass is transferred to the othersurface (FIG. 1(b)). Such a transferred shape of engraved lines on thefront surface and the shape of engraved lines on the back surface havethe same pitch and angle, so that a moire pattern is presumably formedwhen light permeates through the interlayer film for a laminated glassunwound from the rolled body.

As a result of further intensive studies, the present inventors foundout that when the glossiness on the surface of the interlayer film for alaminated glass is higher than a predetermined value or when the hazevalue of the interlayer film for a laminated glass is not higher than apredetermined value, formation of a moire pattern when the interlayerfilm for a laminated glass is unwound from the rolled body can besuppressed. The present invention was thus completed. The moire patternis presumably reduced by suppressing reduction in the lighttransmittance due to the pattern of protrusions and recesses because themoire pattern originates from the cyclic rise and fall of the lighttransmittance on the surface of the film due to the recesses andprotrusions.

The interlayer film for a laminated glass of the present invention has alarge number of recesses on both surfaces. In the interlayer film for alaminated glass of the present invention, the recesses each have agroove shape with a continuous bottom, and adjacent recesses each havinga groove shape with a continuous bottom are regularly parallel to eachother. Commonly, ease of deaeration upon pressure bonding of a laminateincluding an interlayer film for a laminated glass interposed betweentwo glass plates closely relates to the continuousness and smoothness ofthe bottoms of the recesses. When the recesses are in the shape ofengraved lines, the continuousness of the bottoms is further improved tomarkedly increase the deaeration properties.

The term “regularly parallel” means that adjacent recesses each havingthe groove shape mentioned above may be parallel to each other at equalintervals, or adjacent recesses in the shape of engraved lines areparallel to each other, but all of adjacent recesses in the shape ofengraved lines are not necessarily parallel to each other at equalintervals.

FIG. 2 and FIG. 3 each are a view schematically illustrating anexemplary interlayer film for a laminated glass in which recesses eachhaving a groove shape are parallel to each other at equal intervals.FIG. 4 is a view schematically illustrating an exemplary interlayer filmfor a laminated glass in which recesses each having a groove shape areparallel to each other at unequal intervals. In FIG. 4, an interval Abetween a recess 1 and a recess 2 is different from an interval Bbetween the recess 1 and a recess 3. The groove shape does notnecessarily have a straight line shape and may be a wave or zigzag, aslong as the recesses are regularly adjacent and parallel to each other.

The surface having the recesses has a 75° specular gloss measured inconformity with JIS Z 8741-1997 of higher than 3%. The surface havingthe recesses with a glossiness of higher than 3% can suppress formationof a moire pattern when the film is unwound from a rolled body thereof.The glossiness is preferably 4% or higher, still more preferably 7% orhigher.

Since the recesses in the interlayer film for a laminated glass of thepresent invention each have a groove shape with a continuous bottom, theglossiness of the interlayer film may be dependent on the irradiationfrom a light source of a gloss meter. Specifically, the glossiness maychange depending on the angle of the groove shape of each recess of theinterlayer film for a laminated glass relative to the irradiationdirection of the light source. Here, the minimum glossiness obtained bychanging the angle of the groove shape of each recess of the interlayerfilm for a laminated glass relative to the irradiation direction of thelight source is preferably used as the glossiness of the interlayer filmfor a laminated glass of the present invention. In a case where theinterlayer film for a laminated glass has the recesses on both surfaces,the glossiness of higher than 3% needs to be achieved on either onesurface. For further effective suppression of formation of a moirepattern when the interlayer film for a laminated glass is unwound from arolled body thereof, the glossiness is preferably higher than 3% on bothsurfaces.

The glossiness can be measured by the method of measurement 2 describedin JIS Z 8741-1997 with a gloss meter (e.g., “GM-26PRO” available fromMurakami Color Research Laboratory).

The interlayer film for a laminated glass of the present invention has ahaze value measured in conformity with JIS K 7105-1981 of 87% or lower.The interlayer film for a laminated glass with the haze value on thesurface having the recesses of 87% or lower can suppress formation of amoire pattern when unwound from a rolled body thereof. The haze value ispreferably 84% or lower, more preferably 82% or lower.

The haze value can be measured by the method described in JIS K7105-1981 with a haze and transmittance meter (e.g., “HM-150” availablefrom Murakami Color Research Laboratory).

The lower limit of the roughness (Rz) of the surface having the recessesis preferably 10 μm, while the upper limit thereof is preferably 65 μm.With the roughness (Rz) of 10 μm or more, remarkably excellentdeaeration properties can be exhibited. With the roughness (Rz) of 65 μmor less, a moire phenomenon upon unwinding of the film can be reduced.The lower limit of the roughness (Rz) is more preferably 15 μm, whilethe upper limit thereof is more preferably 50 μm. The lower limit isstill more preferably 25 μm, while the upper limit is still morepreferably 40 μm.

The roughness (Rz) of recesses as used herein refers to a ten-pointaverage roughness (Rz) of the obtained interlayer film, determined by amethod in conformity with JIS B-0601 (1994) as defined in JISB-0601(1994) “Surface roughness—definition and indications”. Theroughness (Rz) of the recesses can be measured using, for example, a“Surfcorder SE300” available from Kosaka Laboratory Ltd. as a measuringinstrument. The measurement is performed using a stylus profilometer ata cut-off value of 2.5 mm, a standard length of 2.5 mm, an evaluationlength of 12.5 mm, and a measurement rate of 0.5 mm/s, with a stylushaving a tip radius of 2 μm and a tip angle of 60°. The measurementenvironment is 23° C. and 30 RH %. The stylus is moved in a directionperpendicular to the direction of grooves in the shape of engravedlines.

The recesses on the surface has an interval Sm of preferably 450 μm orless, more preferably 400 μm or less, still more preferably 350 μm orless, particularly preferably 250 μm or less. With such an interval, anautohesion force between faces of the interlayer film for a laminatedglass when the interlayer film for a laminated glass is wound into arolled body is reduced, facilitating unwinding of the film from therolled body.

Normally, when the Sm is smaller, a moire pattern is more likely to beformed. According to the interlayer film for a laminated glass of thepresent invention, however, formation of a moire pattern can besuppressed even when the Sm is 450 μm or less, moreover 350 μm or lessowing to the glossiness set to exceed the predetermined value.

The interval Sm of the recesses as used herein means the averageinterval (Sm) of the recesses on the surface of the obtained interlayerfilm, measured by a method in conformity with JIS B-0601 (1994) asdefined in JIS B-0601 (1994) “Surface roughness—definition andindications”. The interval Sm of the recesses can be measured using a“Surfcorder SE300” available from Kosaka Laboratory Ltd. as a measuringinstrument. The measurement is performed using a stylus profilometer ata cut-off value of 2.5 mm, a standard length of 2.5 mm, an evaluationlength of 12.5 mm, and a measurement rate of 0.5 mm/s, with a stylushaving a tip radius of 2 μm and a tip angle of 60°. The measurementenvironment is 23° C. and 30 RH %. The stylus is moved in a directionperpendicular to the direction of grooves in the shape of engravedlines.

In the interlayer film for a laminated glass, the recesses in the shapeof engraved lines on one surface and the recesses in the shape ofengraved lines on the other surface form an intersection angle θ ofpreferably 10° or more. With such an intersection angle, an autohesionforce between faces of the interlayer film for a laminated glass whenthe interlayer film for a laminated glass is wound into a rolled body isreduced, facilitating unwinding of the film from the rolled body. Theintersection angle θ is more preferably 20° or more, still morepreferably 45° or more, particularly preferably 90°. FIG. 6 is a viewschematically explaining the intersection angle θ. In FIG. 6, aninterlayer film for a laminated glass 10 has recesses 11 each having agroove shape with a continuous bottom illustrated in solid lines on afirst surface and recesses 12 each having a groove shape with acontinuous bottom illustrated in dotted lines on a second surface. Theintersection angle θ refers to an intersection angle formed between therecesses 11 each having a groove shape with a continuous bottomillustrated in solid lines and the recesses 12 each having a grooveshape with a continuous bottom illustrated in dotted lines.

The intersection angle θ is measured for example by observing theinterlayer film for a laminated glass visually or using an opticalmicroscope. In the case of visual observation, the intersection angle θbetween the recesses each having a groove shape with a continuous bottomon the first surface and the recesses each having a groove shape with acontinuous bottom on the second surface is measured by drawing in inkstraight lines parallel to the recesses on both surfaces and measuringthe acute angle formed between the straight lines using a protractor. Inthe case of using an optical microscope, the intersection angle θ can bemeasured by photographing the enlarged surface and measuring the acuteangle using image processing software.

The top portions of protrusions formed in accordance with the recessesin the shape of engraved lines may each have either a planar shape asillustrated in FIG. 2 or a non-planar shape as illustrated in FIG. 3. Inthe case where the protrusions each have a planar top portion, fineprotrusions and recesses may be further formed on the plane of the topportion.

The protrusions may have either the same height or different heights andthe recesses may have either the same depth or different depths as longas the recesses each have a continuous bottom.

For further reduction of the adhesion force (autohesion force) betweenthe interlayer films for a laminated glass stored in the state of beingstacked on each other, the radius of rotation R of the protrusions ispreferably 120 μm or less, more preferably 100 μm or less, still morepreferably 40 μm or less, particularly preferably 25 μm or less. Theradius of rotation R of the protrusions is preferably 50 μm or more,more preferably 120 μm or more, still more preferably 200 μm or more,particularly preferably 300 μm or more, because stress is dispersed uponcontact of protrusions corresponding to recesses in the shape ofengraved lines when the interlayer film for a laminated glass is woundinto a rolled body to prevent the shape of engraved lines on one surfacefrom being transferred to the other surface, thereby further suppressingformation of a moire pattern.

The radius of rotation R of each protrusion can be measured as follows.The interlayer film is cut in a direction perpendicular to the directionof the recesses in the shape of engraved lines and in the thicknessdirection of the film. The cross section is observed using a microscope(e.g., “DSX-100” available from Olympus Corporation) and photographed ata magnification of 277 times. The obtained image is enlarged to 50 μ/20mm for analysis using measurement software included in accessorysoftware. The radius of an inscribed circle at the apex of theprotrusion is determined as the radius of rotation of the protrusion.The measurement is performed in an environment at 23° C. and 30 RH %.

FIG. 5(b) shows a view schematically explaining the radius of rotation Rof the protrusion. In FIG. 5(b), the radius of rotation R is a radius ofa circle in contact with the tip portion of a protrusion 22.

Any method may be employed to set the glossiness of the surface of theinterlayer film for a laminated glass to exceed 3% or set the haze valueof the interlayer film for a laminated glass to 87% or lower and toprovide recesses in the shape of engraved lines on both surfaces.Preferred is a method including: a first step of providing fineprotrusions and recesses to the film surface to set the glossiness ofthe surface of the interlayer film for a laminated glass to exceed 3% orto set the haze value of the interlayer film for a laminated glass to87% or lower; and a second step of providing recesses in the shape ofengraved lines.

The first step of setting the glossiness of the surface of theinterlayer film for a laminated glass to exceed 3% or the haze value ofthe interlayer film for a laminated glass to 87% or lower is notparticularly limited, and is performed by forming fine protrusions andrecesses by, for example, an embossing roll method, a calendar rollmethod, a profile extrusion method, or an embossing method in which meltfracture phenomena are controlled. In particular, the first step can becarried out by the following Production Example 1 or Production Example2.

Production Example 1 is an embossing roll method in which an embossingroll prepared by a specific production method is used. Specifically, anembossing roll is produced by a production process including: a step offorming protrusions and recesses on a metal roll by blasting with anabrasive material (embossing roll production step 1); grinding a portionof each protrusion on the metal roll provided with the protrusions andrecesses into a flat surface portion (embossing roll production step 2);and forming protrusions and recesses on the metal roll by blasting withan abrasive material finer than the abrasive material used in theembossing roll production step 1 (embossing roll production step 3). Theembossing roll is used to set the glossiness of the surface of theinterlayer film for a laminated glass to exceed 3% or to set the hazevalue to 87% or lower.

The metal roll used in the embossing roll production step 1 is made of ametal such as iron, carbon steel, alloy steel, nickel-chromium steel, orchromium steel. Among these, preferred is a roll made of carbon steel oralloy steel for its excellent durability.

In the embossing roll production step 1, a surface of the metal roll isblasted with an abrasive material made of aluminum oxide, silicon oxide,or the like to form protrusions and recesses on the metal roll surface.In particular, aluminum oxide is suitable as an abrasive material.

The grain size of the abrasive material used in the embossing rollproduction step 1 is preferably F20 to F120, more preferably F30 to F80as defined in JIS R6001 (1998).

In the embossing roll production step 1, blasting is performed untildesired roughness is obtained, usually at a discharge pressure of 40×10⁴to 15×10⁵ Pa.

In the embossing roll production step 2, a portion of each protrusionformed on the metal roll in the embossing roll production step 1 isground (partial grinding) into a flat surface portion. Specifically, theupper portion of each protrusion formed on the metal roll is uniformlyground to be smoothened by the partial grinding. This treatment caneliminate excessively large protrusions on the surface of the metalroll.

Usually, aluminum oxide or silicon carbide of F200 to F220 or #240 to#2000, preferably #400 to #1000 specified in JIS, can be used as agrinding stone for partial grinding in the embossing roll productionstep 2. Alternatively, sandpaper can be used as a grinding stone.

In the embossing roll production step 3, protrusions and recesses areformed by blasting with an abrasive material finer than the abrasivematerial used in the embossing roll production step 1.

In the embossing roll production step 3, blasting is performed with anabrasive material made of aluminum oxide, silicon oxide, or the like.

In the embossing roll production step 3, the discharge pressure in theblasting is typically 40×10⁴ to 15×10⁵ Pa.

The grain size of the abrasive material used in the embossing rollproduction step 3 is preferably F150 to F360 or #240 to #700, morepreferably #240 to #400 as defined in JIS R6001 (1998). The use of anabrasive material with such a grain size achieves the desired glossinessor haze value.

The abrasive material used in the embossing roll production step 3preferably has a grain diameter at a cumulative height of 3% inconformity with JIS R6001 (1998) of 150 μm or less, more preferably 125μm or less, still more preferably 103 μm or less. The grain diameter ata cumulative height of 3% within the above preferable range enablesformation of fine protrusions and recesses on the ground part of theroll, so that the glossiness or haze value of the resulting interlayerfilm for laminated glass is prevented from being excessively high.

The abrasive material used in the embossing roll production step 3preferably has a grain diameter at a cumulative height of 94% inconformity with JIS R6001 (1998) of 11 μm or more, more preferably 20 μmor more. With the grain diameter at a cumulative height of 94% withinthe above preferable range, protrusions and recesses to be formed on theground part of the roll can have at least a certain size, so that theinterlayer film obtained has a high glossiness or haze value.

The abrasive material used in the embossing roll production step 3preferably has a grain diameter at a cumulative height of 3% inconformity with JIS R6001 (1998) satisfying the above preferable rangeand a grain diameter at a cumulative height of 94% in conformity withJIS R6001 (1998) satisfying the above preferable range.

The grain size, grain diameter at a cumulative height of 3%, and graindiameter at a cumulative height of 94% are preferably measured by anelectrical resistance test method.

The embossing roll may be subjected to metal plating for rust proofing.Particularly preferred is chemical plating because uniform platingthickness can be achieved.

In Production Example 1, the embossing roll produced by the productionmethod is used to set the glossiness of the surface of the interlayerfilm for a laminated glass to exceed 3% or to set the haze value to 87%or lower by an embossing roll method.

Conditions of the embossing roll method may be as follows: a filmtemperature of 80° C., an embossing roll temperature of 145° C., alinear velocity of 10 m/min, and a linear pressure within a range of 1to 100 kN/m.

Production Example 2 is an embossing method in which melt fracturephenomena are controlled. This method adjusts the cooling rate of aninterlayer film for a laminated glass formed of a resin composition forforming an interlayer film for a laminated glass after extrusion from adie. In the embossing method in which melt fracture phenomena arecontrolled, a film extruded from a die is cooled in a cooling watertank. In this operation, the cooling rate of the film can be adjusted tothereby control the glossiness or haze value of a first shape to beformed. Specifically, the first shape satisfying the intended glossinessor haze value can be formed by shortening the distance from the die tothe cooling water tank and increasing the cooling rate of the film toincrease the value of the glossiness or haze value. The distance betweenthe die and the cooling water tank is preferably 250 mm or shorter, morepreferably 200 mm or shorter, still more preferably 150 mm or shorter,particularly preferably 100 mm or shorter, most preferably 50 mm orshorter.

Preferred ranges of other conditions for film formation in ProductionExample 2 are as follows: an extrusion amount per die width of 100 to700 kg/hr·m, a surface temperature of the film immediately afterextrusion from the die of 140° C. to 260° C., a resin pressure at thedie inlet of 30 to 160 kgf/cm², and a water temperature in the watertank for cooling the film of 20° C. to 30° C. Each condition iscontrolled to achieve the desired extrusion amount and Rz value.

The second step of forming the recesses in the shape of engraved linesis not particularly limited, and is performed by, for example, anembossing roll method, a calendar roll method, or a profile extrusionmethod. In particular, the embossing roll method is preferred becausethe state where the recesses in the shape of engraved lines are adjacentand parallel to each other can be easily achieved.

The interlayer film for a laminated glass of the present invention mayhave a single layer structure consisting of one resin layer or amultilayer structure including two or more resin layers laminatedtogether.

In the case of having a multilayer structure, the interlayer film for alaminated glass of the present invention may include, as two or moreresin layers mentioned above, a first resin layer and a second resinlayer having different characteristics. Such an interlayer film for alaminated glass can have various properties which are hardly achieved bya single layer structure.

The resin layer preferably contains a thermoplastic resin.

Examples of the thermoplastic resin include polyvinylidene fluoride,polytetrafluoroethylene, vinylidene fluoride-propylene hexafluoridecopolymers, polyethylene trifluoride, acrylonitrile-butadiene-styrenecopolymers, polyester, polyether, polyamide, polycarbonate,polyacrylate, polymethacrylate, polyvinyl chloride, polyethylene,polypropylene, polystyrene, polyvinyl acetal, and ethylene-vinyl acetatecopolymers. In particular, the resin layer preferably contains polyvinylacetal or an ethylene-vinyl acetate copolymer, more preferably containspolyvinyl acetal.

The polyvinyl acetal can be prepared, for example, by acetalization ofpolyvinyl alcohol with an aldehyde. The polyvinyl alcohol can beproduced, for example, by saponification of polyvinyl acetate. Thepolyvinyl alcohol commonly has a degree of saponification within a rangeof 70 to 99.8 mol %.

The polyvinyl alcohol has an average degree of polymerization ofpreferably 200 or more, more preferably 500 or more, still morepreferably 1,700 or more, particularly preferably more than 1,700, andpreferably 5,000 or less, more preferably 4,000 or less, still morepreferably 3,000 or less, particularly preferably less than 3,000. Whenthe average degree of polymerization is equal to or more than the lowerlimit, a laminated glass to be obtained has higher penetrationresistance. When the average degree of polymerization is equal to orless than the upper limit, formation of an interlayer film isfacilitated.

The average degree of polymerization of the polyvinyl alcohol can beobtained by the method in conformity with JIS K6726 “Testing methods forpolyvinyl alcohol”.

The carbon number of an acetal group contained in the polyvinyl acetalis not particularly limited. The aldehyde for use in production of thepolyvinyl acetal is not particularly limited. The lower limit of thecarbon number of the acetal group in the polyvinyl acetal is preferably3, and the upper limit thereof is preferably 6. When the carbon numberof the acetal group in the polyvinyl acetal is 3 or more, an interlayerfilm has a sufficiently low glass transition temperature, and bleedingout of a plasticizer can be prevented. When the carbon number of thealdehyde is 6 or less, synthesis of the polyvinyl acetal can befacilitated to ensure the productivity. The C3-C6 aldehyde may be alinear or branched aldehyde, and examples thereof includen-butyraldehyde and n-valeraldehyde.

The aldehyde is not particularly limited. Commonly, the aldehyde ispreferably a C1-C10 aldehyde. Examples of the C1-C10 aldehyde includepropionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, formaldehyde, acetaldehyde, and benzaldehyde. Preferredamong these are propionaldehyde, n-butyraldehyde, isobutyraldehyde,n-hexylaldehyde, and n-valeraldehyde, more preferred arepropionaldehyde, n-butyraldehyde, and isobutyraldehyde, and still morepreferred is n-butyraldehyde. These aldehydes may be used alone or incombination of two or more thereof.

The hydroxy group content of the polyvinyl acetal is preferably 10 mol %or higher, more preferably 15 mol % or higher, still more preferably 18mol % or higher, and preferably 40 mol % or lower, more preferably 35mol % or lower. When the hydroxy group content is equal to or more thanthe lower limit, an interlayer film has a higher adhesion force. Whenthe hydroxy group content is equal to or less than the upper limit, aninterlayer film has high flexibility and is easily handled.

The hydroxy group content of the polyvinyl acetal is a value inpercentage of the mole fraction obtained by dividing the amount ofethylene groups to which hydroxy groups are bonded by the total amountof ethylene groups of the main chain. The amount of ethylene groups towhich hydroxy groups are bonded can be determined, for example, bymeasurement in conformity with JIS K6726 “Testing methods for polyvinylalcohol” or in conformity with ASTM D1396-92.

The degree of acetylation (acetyl group content) of the polyvinyl acetalis preferably 0.1 mol % or more, more preferably 0.3 mol % or more,still more preferably 0.5 mol % or more, and preferably 30 mol % orless, more preferably 25 mol % or less, still more preferably 20 mol %or less. When the degree of acetylation is equal to or more than thelower limit, the polyvinyl acetal has high compatibility with aplasticizer. When the degree of acetylation is equal to or less than theupper limit, an interlayer film and a laminated glass to be obtainedhave high damp resistance.

The degree of acetylation is a value in percentage of the mole fractionobtained by subtracting the amount of ethylene groups to which acetalgroups are bonded and the amount of ethylene groups to which hydroxygroups are bonded from the total amount of ethylene groups of the mainchain and then dividing the obtained value by the total amount ofethylene groups of the main chain. The amount of ethylene groups towhich acetal groups are bonded can be measured, for example, inconformity with JIS K6728 “Testing methods for polyvinyl butyral” or inconformity with ASTM D1396-92.

The degree of acetalization of the polyvinyl acetal (or the degree ofbutyralization of a polyvinyl butyral resin) is preferably 50 mol % ormore, more preferably 53 mol % or more, still more preferably 60 mol %or more, particularly preferably 63 mol % or more, and preferably 85 mol% or less, more preferably 75 mol % or less, still more preferably 70mol % or less. When the degree of acetalization is equal to or more thanthe lower limit, the polyvinyl acetal has high compatibility with aplasticizer. When the degree of acetalization is equal to or less thanthe upper limit, a reaction time necessary for production of thepolyvinyl acetal is short.

The degree of acetalization is a value in percentage of the molefraction obtained by dividing the amount of ethylene groups to whichacetal groups are bonded by the total amount of ethylene groups of themain chain.

The degree of acetalization can be calculated by measuring the degree ofacetylation and the hydroxy group content by the method in conformitywith JIS K6728 “Testing methods for polyvinyl butyral” or the method inconformity with ASTM D1396-92, calculating their mole fractions from theobtained measurement results, and subsequently subtracting the molefractions of the degree of acetylation and the hydroxy group contentfrom 100 mol %.

The hydroxy group content, the degree of acetalization (degree ofbutyralization), and the degree of acetylation are preferably calculatedfrom results of measurement by the method in conformity with JIS K6728“Testing methods for polyvinyl butyral”. In the case where the polyvinylacetal is a polyvinyl butyral resin, the hydroxy group content, thedegree of acetalization (degree of butyralization), and the degree ofacetylation are preferably calculated from results of measurement by themethod in conformity with JIS K6728 “Testing methods for polyvinylbutyral”.

The resin layer preferably contains polyvinyl acetal and a plasticizer.

Any plasticizer may be used as long as it is commonly used in interlayerfilms for a laminated glass. Examples thereof include organicplasticizers such as monobasic organic acid esters and polybasic organicacid esters, and phosphoric acid plasticizers such as organophosphatecompounds and organophosphite compounds.

Examples of the organic plasticizers include triethyleneglycol-di-2-ethylhexanoate, triethylene glycol-di-2-ethylbutyrate,triethylene glycol-di-n-heptanoate, tetraethyleneglycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylbutyrate,tetraethylene glycol-di-n-heptanoate, diethyleneglycol-di-2-ethylhexanoate, diethylene glycol-di-2-ethylbutyrate, anddiethylene glycol-di-n-heptanoate. Among these, the resin layer containspreferably triethylene glycol-di-2-ethylhexanoate, triethyleneglycol-di-2-ethylbutyrate, or triethylene glycol-di-n-heptanoate, morepreferably triethylene glycol-di-2-ethylhexanoate.

The plasticizer content is not particularly limited. The plasticizercontent based on 100 parts by mass of the thermoplastic resin ispreferably 25 parts by mass or more, more preferably 30 parts by mass ormore, and preferably 80 parts by mass or less, more preferably 70 partsby mass or less. When the plasticizer content is equal to or more thanthe lower limit, a laminated glass to be obtained has higher penetrationresistance. When the plasticizer content is equal to or less than theupper limit, an interlayer film has higher transparency.

The resin layer preferably contains an adhesion modifier. In particular,the resin layer to be in contact with a glass plate in production of alaminated glass preferably contains an adhesion modifier.

As the adhesion modifier, for example, an alkali metal salt or analkaline earth metal salt is preferably used. Examples of the adhesionmodifier include salts such as potassium, sodium, and magnesium salts.

Examples of an acid forming the salts include organic carboxylic acidssuch as octylic acid, hexylic acid, 2-ethylbutyric acid, butyric acid,acetic acid, and formic acid, and inorganic acids such as hydrochloricacid and nitric acid. The resin layer to be in contact with a glassplate preferably contains magnesium salt as an adhesion modifier becausethe adhesion force between the glass plate and the resin layer can beeasily adjusted in production of a laminated glass.

The resin layer may optionally contain additives such as an antioxidant,a light stabilizer, a modified silicone oil as an adhesion modifier, aflame retardant, an antistatic agent, a damp proofing agent, a heat rayreflecting agent, and a heat ray absorbing agent.

The thickness of the interlayer film for a laminated glass of thepresent invention is not particularly limited. The thickness of theinterlayer film is preferably 0.1 mm or more, more preferably 0.25 mm ormore, and preferably 3 mm or less, more preferably 1.5 mm or less, froma practical standpoint and from the viewpoint of sufficiently enhancingheat shielding properties. When the thickness of the interlayer film isequal to or more than the lower limit, a laminated glass to be obtainedhas high penetration resistance.

The interlayer film for a laminated glass of the present invention maybe produced by any method. A conventionally known method can be employedin production of the interlayer film. For example, a thermoplastic resinand other optional components to be contained, such as the component X,are kneaded and molded into an interlayer film. Extrusion molding issuitable for continuous production and is therefore preferred forproduction of the interlayer film.

Preferably, the interlayer film for a laminated glass of the presentinvention includes, as two or more resin layers mentioned above, atleast a first resin layer and a second resin layer, and polyvinyl acetalcontained in the first resin layer (hereafter, referred to as polyvinylacetal A) has a hydroxy group content different from that of polyvinylacetal contained in the second resin layer (hereafter, referred to aspolyvinyl acetal B).

Due to different characteristics of the polyvinyl acetal A and thepolyvinyl acetal B, an interlayer film for a laminated glass to beprovided can have various properties which are hardly achieved by asingle layer structure. For example, in a case where the first resinlayer is interposed between two second resin layers and the polyvinylacetal A has a lower hydroxy group content than the polyvinyl acetal B,the first resin layer tends to have a lower glass transition temperaturethan the second resin layer. As a result, the first resin layer issofter than the second resin layer, leading to higher sound insulationproperties of the interlayer film for a laminated glass. In a case wherethe first resin layer is interposed between two second resin layers andthe polyvinyl acetal A has a higher hydroxy group content than thepolyvinyl acetal B, the first resin layer tends to have a higher glasstransition temperature than the second resin layer. As a result, thefirst resin layer is harder than the second resin layer, leading tohigher penetration resistance of the interlayer film for a laminatedglass.

In the case where the first resin layer and the second resin layer eachcontain a plasticizer, the plasticizer content (hereafter, referred toas content A) of the first resin layer based on 100 parts by mass of thepolyvinyl acetal is preferably different from the plasticizer content(hereafter, referred to as content B) of the second resin layer based on100 parts by mass of the polyvinyl acetal. For example, in a case wherethe first resin layer is interposed between two second resin layers andthe content A is higher than the content B, the first resin layer tendsto have a lower glass transition temperature than the second resinlayer. As a result, the first resin layer is softer than the secondresin layer, leading to higher sound insulation properties of theinterlayer film for a laminated glass. In a case where the first resinlayer is interposed between two second resin layers and the content A islower than the content B, the first resin layer tends to have a higherglass transition temperature than the second resin layer. As a result,the first resin layer is harder than the second resin layer, leading tohigher penetration resistance of the interlayer film for a laminatedglass.

The combination of two or more resin layers included in the interlayerfilm for a laminated glass of the present invention may be, for example,a sound insulation layer as the first resin layer and a protective layeras the second resin layer with an aim of improving the sound insulationproperties of a laminated glass to be obtained. For higher soundinsulation properties of a laminated glass to be obtained, preferably,the sound insulation layer contains polyvinyl acetal X and aplasticizer, and the protective layer contains polyvinyl acetal Y and aplasticizer. Moreover, in a case where the sound insulation layer isinterposed between two protective layers, the resulting interlayer filmfor a laminated glass (hereafter, also referred to as a sound insulationinterlayer film) can have excellent sound insulation properties. Thesound insulation interlayer film is more specifically described in thefollowing.

In the sound insulation interlayer film, the sound insulation layerimparts sound insulation properties. The sound insulation layerpreferably contains the polyvinyl acetal X and a plasticizer.

The polyvinyl acetal X can be prepared by acetalization of polyvinylalcohol with an aldehyde. The polyvinyl alcohol is commonly obtained bysaponifying polyvinyl acetate.

The lower limit of the average degree of polymerization of the polyvinylalcohol is preferably 200, and the upper limit thereof is preferably5,000. When the polyvinyl alcohol has an average degree ofpolymerization of 200 or more, a sound insulation interlayer film to beobtained can have better penetration resistance. When the polyvinylalcohol has an average degree of polymerization of 5,000 or less,formability of a sound insulation layer can be ensured. Concerning theaverage degree of polymerization of the polyvinyl alcohol, the lowerlimit is more preferably 500 and the upper limit is more preferably4,000.

The average degree of polymerization of the polyvinyl alcohol isobtained by a method in conformity with JIS K6726 “Testing methods forpolyvinyl alcohol”.

The lower limit of the carbon number of the aldehyde used foracetalization of the polyvinyl alcohol is preferably 4, and the upperlimit thereof is preferably 6. When the aldehyde has a carbon number of4 or more, a sound insulation interlayer film for a laminated glass tobe obtained can stably contain a sufficient amount of a plasticizer. Asa result, the sound insulation interlayer film can exhibit excellentsound insulation properties. Moreover, bleeding out of the plasticizercan be prevented. When the aldehyde has a carbon number of 6 or less,synthesis of the polyvinyl acetal X can be facilitated, ensuring theproductivity. The C4-C6 aldehyde may be a linear or branched aldehyde,and examples thereof include n-butyraldehyde and n-valeraldehyde.

The upper limit of the hydroxy group content of the polyvinyl acetal Xis preferably 30 mol %. When the hydroxy group content of the polyvinylacetal X is 30 mol % or lower, the sound insulation layer can contain aplasticizer in an amount needed for exhibiting sound insulationproperties, and bleeding out of the plasticizer can be prevented. Theupper limit of the hydroxy group content of the polyvinyl acetal X ismore preferably 28 mol %, still more preferably 26 mol %, particularlypreferably 24 mol %, and the lower limit thereof is preferably 10 mol %,more preferably 15 mol %, still more preferably 20 mol %. The hydroxygroup content of the polyvinyl acetal X is a value in percentage of themole fraction (mol %) obtained by dividing the amount of ethylene groupsto which hydroxy groups are bonded by the total amount of ethylenegroups of the main chain. The amount of ethylene groups to which hydroxygroups are bonded can be determined by measuring the amount of ethylenegroups to which hydroxy groups are bonded in the polyvinyl acetal X bythe method in conformity with JIS K6728 “Testing methods for polyvinylbutyral”.

The lower limit of the acetal group content of the polyvinyl acetal X ispreferably 60 mol %, and the upper limit thereof is preferably 85 mol %.When the polyvinyl acetal X has an acetal group content of 60 mol % ormore, the sound insulation layer has higher hydrophobicity and cancontain a plasticizer in an amount needed for exhibiting soundinsulation properties. Moreover, bleeding out of the plasticizer andwhitening can be prevented. When the polyvinyl acetal X has an acetalgroup content of 85 mol % or less, synthesis of the polyvinyl acetal Xcan be facilitated, ensuring the productivity. The lower limit of theacetal group content of the polyvinyl acetal X is more preferably 65 mol%, still more preferably 68 mol % or more.

The acetal group content can be obtained by measuring the amount ofethylene groups to which acetal groups are bonded in the polyvinylacetal X by the method in conformity with JIS K6728 “Testing methods forpolyvinyl butyral”.

The lower limit of the acetyl group content of the polyvinyl acetal X ispreferably 0.1 mol %, and the upper limit thereof is preferably 30 mol%. When the acetyl group content of the polyvinyl acetal X is 0.1 mol %or more, the sound insulation layer can contain a plasticizer in anamount needed for exhibiting sound insulation properties, and bleedingout of the plasticizer can be prevented. When the acetyl group contentof the polyvinyl acetal X is 30 mol % or less, the sound insulationlayer can have higher hydrophobicity, preventing whitening. The lowerlimit of the acetyl group content is more preferably 1 mol %, still morepreferably 5 mol %, particularly preferably 8 mol %, and the upper limitthereof is more preferably 25 mol %, still more preferably 20 mol %. Theacetyl group content is a value in percentage of the mole fraction (mol%) obtained by subtracting the amount of ethylene groups to which acetalgroups are bonded and the amount of ethylene groups to which hydroxygroups are bonded from the total amount of ethylene groups of the mainchain and then dividing the obtained value by the total amount ofethylene groups of the main chain.

The polyvinyl acetal X is preferably a polyvinyl acetal having an acetylgroup content of 8 mol % or more or a polyvinyl acetal having an acetylgroup content of less than 8 mol % and an acetal group content of 65 mol% or more because the sound insulation layer can readily contain aplasticizer in an amount needed for exhibiting sound insulationproperties. Moreover, the polyvinyl acetal X is more preferably apolyvinyl acetal having an acetyl group content of 8 mol % or more or apolyvinyl acetal having an acetyl group content of less than 8 mol % andan acetal group content of 68 mol % or more.

The lower limit of the plasticizer content of the sound insulation layerbased on 100 parts by mass of the polyvinyl acetal X is preferably 45parts by mass, and the upper limit thereof is preferably 80 parts bymass. When the plasticizer content is 45 parts by mass or more, thesound insulation layer can exhibit high sound insulation properties.When the plasticizer content is 80 parts by mass or less, reduction inthe transparency and adhesiveness of an interlayer film for a laminatedglass to be obtained due to bleeding out of the plasticizer can beprevented. The lower limit of the plasticizer content is more preferably50 parts by mass, still more preferably 55 parts by mass, and the upperlimit thereof is more preferably 75 parts by mass, still more preferably70 parts by mass.

In the case where the sound insulation layer has a rectangularcross-sectional shape in the thickness direction, the lower limit of thethickness is preferably 50 μm. Having a thickness of 50 μm or more, thesound insulation layer can exhibit enough sound insulation properties.The lower limit of the thickness of the sound insulation layer is morepreferably 80 μm. The upper limit thereof is not particularly limited.In consideration of the thickness as an interlayer film for a laminatedglass, the upper limit is preferably 300 μm.

The sound insulation layer may have one end and the other end on anopposite side of the one end, and may have a shape in which thethickness of the other end is greater than the thickness of the one end.The sound insulation layer preferably has a wedge portion in across-sectional shape in the thickness direction. In this case, thelower limit of the minimum thickness of the sound insulation layer ispreferably 50 μm. Having the minimum thickness of 50 μm or more, thesound insulation layer can exhibit enough sound insulation properties.The lower limit of the minimum thickness of the sound insulation layeris more preferably 80 μm, still more preferably 100 μm. The upper limitof the maximum thickness of the sound insulation layer is notparticularly limited. The upper limit is preferably 300 μm inconsideration of the thickness as an interlayer film for a laminatedglass. The upper limit of the maximum thickness of the sound insulationlayer is more preferably 220 μm.

The protective layer prevents bleeding out of the plasticizer containedin a large amount in the sound insulation layer to prevent reduction inthe adhesiveness between the interlayer film for a laminated glass andthe glass plate, and imparts penetration resistance to the interlayerfilm for a laminated glass.

The protective layer preferably contains, for example, a plasticizer andthe polyvinyl acetal Y, more preferably a plasticizer and the polyvinylacetal Y having a higher hydroxy group content than the polyvinyl acetalX.

The polyvinyl acetal Y can be prepared by acetalization of polyvinylalcohol with an aldehyde. The polyvinyl alcohol is commonly obtained bysaponifying polyvinyl acetate.

The lower limit of the average degree of polymerization of the polyvinylalcohol is preferably 200, and the upper limit thereof is preferably5,000. When the polyvinyl alcohol has an average degree ofpolymerization of 200 or more, an interlayer film for a laminated glassto be obtained can have better penetration resistance. When thepolyvinyl alcohol has an average degree of polymerization of 5,000 orless, formability of a protective layer can be ensured. Concerning theaverage degree of polymerization of the polyvinyl alcohol, the lowerlimit is more preferably 500 and the upper limit is more preferably4,000.

The lower limit of the carbon number of the aldehyde used foracetalization of the polyvinyl alcohol is preferably 3, and the upperlimit thereof is preferably 4. When the aldehyde has a carbon number of3 or more, an interlayer film for a laminated glass to be obtained hashigher penetration resistance. When the aldehyde has a carbon number of4 or less, productivity of the polyvinyl acetal Y is improved.

The C3-C4 aldehyde may be a linear or branched aldehyde, and examplesthereof include n-butyraldehyde.

The upper limit of the hydroxy group content of the polyvinyl acetal Yis preferably 33 mol %, and the lower limit thereof is preferably 28 mol%. When the polyvinyl acetal Y has a hydroxy group content of 33 mol %or lower, whitening of an interlayer film for a laminated glass to beobtained can be prevented. When the polyvinyl acetal Y has a hydroxygroup content of 28 mol % or more, an interlayer film for a laminatedglass to be obtained has higher penetration resistance.

The lower limit of the acetal group content of the polyvinyl acetal Y ispreferably 60 mol %, and the upper limit thereof is preferably 80 mol %.When the acetal group content is 60 mol % or more, a protective layer tobe obtained can contain a plasticizer in an amount needed for exhibitingenough penetration resistance. When the acetal group content is 80 mol %or less, the adhesion force between the protective layer and the glassplate can be ensured. The lower limit of the acetal group content ismore preferably 65 mol %, and the upper limit thereof is more preferably69 mol %.

The upper limit of the acetyl group content of the polyvinyl acetal Y ispreferably 7 mol %. When the polyvinyl acetal Y has an acetyl groupcontent of 7 mol % or less, a protective layer to be obtained can havehigher hydrophobicity, thereby preventing whitening. The upper limit ofthe acetyl group content is more preferably 2 mol %, and the lower limitthereof is preferably 0.1 mol %. The hydroxy group contents, acetalgroup contents, and acetyl group contents of the polyvinyl acetals A, B,and Y can be measured by the same methods as those in the case of thepolyvinyl acetal X.

The lower limit of the plasticizer content of the protective layer basedon 100 parts by mass of the polyvinyl acetal Y is preferably 20 parts bymass, and the upper limit thereof is preferably 45 parts by mass. Whenthe plasticizer content is 20 parts by mass or more, the penetrationresistance can be ensured. When the plasticizer content is 45 parts bymass or less, bleeding out of the plasticizer can be prevented, therebypreventing reduction in the transparency and adhesiveness of aninterlayer film for a laminated glass to be obtained. The lower limit ofthe plasticizer content is more preferably 30 parts by mass, still morepreferably 35 parts by mass, and the upper limit thereof is morepreferably 43 parts by mass, still more preferably 41 parts by mass. Forbetter sound insulation properties of a laminated glass to be obtained,the plasticizer content of the protective layer is preferably lower thanthe plasticizer content of the sound insulation layer.

For higher sound insulation properties of a laminated glass to beobtained, the hydroxy group content of the polyvinyl acetal Y ispreferably higher than the hydroxy group content of the polyvinyl acetalX, more preferably higher by 1 mol % or more, still more preferablyhigher by 5 mol % or more, particularly preferably higher by 8 mol % ormore. Adjustment of the hydroxy group contents of the polyvinyl acetal Xand polyvinyl acetal Y enables control of the plasticizer contents ofthe sound insulation layer and the protective layer, so that the soundinsulation layer has a lower glass transition temperature. As a result,a laminated glass to be obtained has higher sound insulation properties.

For still higher sound insulation properties of a laminated glass to beobtained, the plasticizer content of the sound insulation layer(hereafter, also referred to as content X) based on 100 parts by mass ofthe polyvinyl acetal X is preferably higher than the plasticizer contentof the protective layer (hereafter, also referred to as content Y) basedon 100 parts by mass of the polyvinyl acetal Y, more preferably higherby 5 parts by mass or more, still more preferably higher by 15 parts bymass or more, particularly preferably higher by 20 parts by mass ormore. Adjustment of the content X and content Y lowers the glasstransition temperature of the sound insulation layer. As a result, alaminated glass to be obtained has still higher sound insulationproperties.

The protective layer may have any thickness, provided that it canfulfill the role as the protective layer. In a case where protrusionsand recesses are formed on the protective layer, the protective layer ispreferably as thick as possible to prevent the protrusions and recessesfrom being transferred to the interface with the sound insulation layerdirectly in contact with the protective layer. Specifically, the lowerlimit of the thickness of the protective layer having a rectangularcross-sectional shape is preferably 100 μm, more preferably 300 μm,still more preferably 400 μm, particularly preferably 450 μm. The upperlimit of the thickness of the protective layer is not particularlylimited. In order to ensure the thickness of the sound insulation layerenough to achieve sufficient sound insulation properties, the upperlimit of the protective layer is practically about 500 μm.

The protective layer may have one end and the other end on an oppositeside of the one end, and may have a shape in which the thickness of theother end is greater than the thickness of the one end. The protectivelayer preferably has a wedge portion in a cross-sectional shape in thethickness direction. The protective layer may have any thickness,provided that it can fulfill the role as the protective layer. In a casewhere protrusions and recesses are formed on the protective layer, theprotective layer is preferably as thick as possible to prevent theprotrusions and recesses from being transferred to the interface withthe sound insulation layer directly in contact with the protectivelayer. Specifically, the lower limit of the minimum thickness of theprotective layer is preferably 100 μm, more preferably 300 μm, stillmore preferably 400 μm, particularly preferably 450 μm. The upper limitof the maximum thickness of the protective layer is not particularlylimited. In order to ensure the thickness of the sound insulation layerenough to achieve sufficient sound insulation properties, the upperlimit of the protective layer is practically about 1,000 μm, preferably800 μm.

The interlayer film for a laminated glass of the present invention mayhave one end and the other end on an opposite side of the one end. Theone end and the other end are end portions on both sides facing eachother in the interlayer film. In the interlayer film for a laminatedglass of the present invention, the thickness of the other end ispreferably greater than the thickness of the one end. A laminated glassprepared using the interlayer film for a laminated glass of the presentinvention having such a shape where the thickness is different betweenone end and the other end can be suitably used in a head-up display. Inthis case, occurrence of double images can be effectively suppressed.The interlayer film for a laminated glass of the present invention mayhave a wedge cross-sectional shape. Provided that the interlayer filmfor a laminated glass has a wedge cross-sectional shape, a head-updisplay can perform image display without occurrence of double images byadjusting wedge angle θ of the wedge shape according to the mountingangle of the laminated glass. The lower limit of the wedge angle θ ispreferably 0.1 mrad, more preferably 0.2 mrad, still more preferably 0.3mrad, and the upper limit thereof is preferably 1 mrad, more preferably0.9 mrad, from the viewpoint of further suppressing the occurrence ofdouble images. In the case of producing the interlayer film for alaminated glass having a wedge cross-sectional shape, for example, byextrusion molding of a resin composition using an extruder, the producedinterlayer film may have a shape having the minimum thickness in aregion slightly inward from the end on the thinner side (specifically,when the distance from one end to the other end is defined as X, aregion within a distance of 0X to 0.2X inward from the end on thethinner side) and having the maximum thickness in a region slightlyinward from the end on the thicker side (specifically, when the distancefrom one end to the other end is defined as X, a region within adistance of 0X to 0.2X inward from the end on the thicker side). Such ashape is herein also included in the wedge shape.

The sound insulation interlayer film may be produced by any method. Thesound insulation interlayer film can be produced, for example, by amethod of forming the sound insulation layer and protective layer assheet materials by a conventional film-forming method such as extrusion,calendering, or pressing and then stacking the obtained sheet materials.

The present invention also encompasses a laminated glass including theinterlayer film for a laminated glass of the present inventioninterposed between a pair of glass plates.

The glass plate may be a commonly used transparent glass plate. Examplesthereof include inorganic glass plates such as float glass plates,polished glass plates, figured glass plates, meshed glass plates, wiredglass plates, colored glass plates, heat-absorbing glass plates,heat-reflecting glass plates, and green glass plates. An ultravioletshielding glass plate including an ultraviolet shielding coat layer on aglass surface may also be used. Moreover, also usable are organicplastic plates made of polyethylene terephthalate, polycarbonate,polyacrylate, or the like.

The glass plates may include two or more types of glass plates. Forexample, the laminated glass may be a laminated glass including theinterlayer film for a laminated glass of the present invention between atransparent float glass plate and a colored glass plate such as a greenglass plate. The glass plates may include two or more glass plates withdifferent thicknesses.

Advantageous Effects of Invention

The present invention can provide an interlayer film for a laminatedglass having recesses in the shape of engraved lines on both surfaces toexhibit excellent deaeration properties in production of a laminatedglass and suppressing formation of a moire pattern when unwound from arolled body thereof. The present invention also can provide a laminatedglass including the interlayer film for a laminated glass, a method forproducing an embossing roll suitably used for production of theinterlayer film for a laminated glass, and a method for producing theinterlayer film for a laminated glass.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows views schematically explaining a cause of a moire patternformed when an interlayer film for a laminated glass having recesses inthe shape of engraved lines is unwound from a rolled body thereof.

FIG. 2 shows a view schematically illustrating an exemplary interlayerfilm for a laminated glass in which recesses each having a groove shapewith a continuous bottom are arranged on the surface at equal intervalsand adjacent recesses are parallel to each other.

FIG. 3 shows a view schematically illustrating an exemplary interlayerfilm for a laminated glass in which recesses each having a groove shapewith a continuous bottom are arranged on the surface at equal intervalsand adjacent recesses are parallel to each other.

FIG. 4 shows a view schematically illustrating an exemplary interlayerfilm for a laminated glass in which recesses each having a groove shapewith a continuous bottom are arranged on the surface at unequalintervals and adjacent recesses are parallel to each other.

FIG. 5 shows views schematically explaining the radius of rotation R ofa protrusion.

FIG. 6 is a view schematically explaining the intersection angle θ.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are more specifically described inthe following with reference to, but not limited to, examples.

Example 1 (1) Preparation of a Resin Composition

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral (acetylgroup content: 1 mol %, butyral group content: 69 mol %, hydroxy groupcontent: 30 mol %). To 100 parts by mass of the polyvinyl butyral wasadded 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO)as a plasticizer, and kneaded well with a mixing roll to give a resincomposition.

(2) Production of an Interlayer Film for a Laminated Glass

The obtained resin composition was extruded from an extruder to form aninterlayer film for a laminated glass with a uniform thickness.

(3) Formation of Fine Protrusions and Recesses in the First Step

According to Production Example 1, fine protrusions and recesses wereformed on both surfaces (first surface and second surface) of theinterlayer film for a laminated glass to adjust the glossiness of thesurface.

Here, an embossing roll produced by the following method was used.

As an embossing roll production step 1, blasting was performed on thesurface of a metal roll using a #36 abrasive material made of aluminumoxide at a discharge pressure of 50×10⁴ Pa. After the embossing rollproduction step 1, the ten-point average roughness Rz of the rollsurface measured in conformity with JIS B-0601 (1994) was 65 μm.

Next, as an embossing roll production step 2, partial grinding wasperformed using a #400 to #1000 grinding stone. After the embossing rollproduction step 2, the ten-point average roughness Rz of the rollsurface measured in conformity with JIS B-0601 (1994) was 40 μm.

Then, as an embossing roll production step 3, blasting was performedusing #320 abrasive material made of aluminum oxide at a dischargepressure of 50×10⁴ Pa, thereby preparing an embossing roll.

A pair of thus prepared embossing rolls was used as a device fortransferring a pattern of protrusions and recesses to form fineprotrusions and recesses on both surfaces of the obtained interlayerfilm for a laminated glass. The transferring conditions employed herewere a temperature of the interlayer film for a laminated glass of 80°C., a temperature of the rolls of 145° C., a linear velocity of 10m/min, a line width of 1.5 m, and a linear pressure of 1 to 100 kN/m.

The ten-point average roughness (Rz) of the film surface after theformation of fine protrusions and recesses measured in conformity withJIS B-0601 was 12 μm. The obtained interlayer film had an averagethickness of 760 μm.

(4) Formation of Recesses in the Shape of Engraved Lines by Second Step

To the surface of the interlayer film for a laminated glass after thefirst step was provided protrusions and recesses each having a grooveshape with a continuous bottom by the following procedure. A pair ofrolls including a metal roll having a surface processed with atriangular oblique line-type mill and a rubber roll having a JIShardness of 45 to 75 was used as a device for transferring a pattern ofprotrusions and recesses. The interlayer film for a laminated glassafter the first step was passed through the device for transferring apattern of protrusions and recesses, thereby forming protrusions andrecesses where recesses each having a groove shape with a continuousbottom are parallel to each other at equal intervals on the firstsurface of the interlayer film for a laminated glass. The transferringconditions employed here were a temperature of the interlayer film for alaminated glass of 70° C., a temperature of the rolls of 140° C., alinear velocity of 10 m/min, and a linear pressure to 1 to 100 kN/m forproducing the desired roughness.

Then, the same operations were performed on the second surface of theinterlayer film for a laminated glass to form recesses each having agroove shape with a continuous bottom. At that time, the intersectionangle formed between the recesses each having a groove shape (shape ofan engraved line) with a continuous bottom on the first surface and therecesses each having a groove shape (shape of an engraved line) with acontinuous bottom on the second surface was set to 20°.

(5) Measurement of Protrusions and Recesses on the First Surface and theSecond Surface (5-1) Glossiness Measurement

The glossiness was measured using a gloss meter (“GM-26PRO” availablefrom Murakami Color Research Laboratory) by the method of measurement 2described in JIS Z 8741-1997. The interlayer film for a laminated glasswas left to stand on a sample table, and the glossiness was measuredwhile the interlayer film for a laminated glass was rotated so that theangle of the groove shape of each recess relative to the irradiationdirection of a light source was changed. Here, the minimum glossinesswas taken as the glossiness of the interlayer film for a laminated glassof the present invention.

(5-2) Rz Value Measurement

The ten-point average roughness (Rz) on both surfaces of the obtainedinterlayer film for a laminated glass was measured by the method inconformity with JIS B-0601 (1994) using “Surfcorder SE300” availablefrom Kosaka Laboratory Ltd. The measurement was performed using a stylusprofilometer at a cut-off value of 2.5 mm, a standard length of 2.5 mm,an evaluation length of 12.5 mm, and a measurement rate of 0.5 mm/s,with a stylus having a tip radius of 2 μm and a tip angle of 60°. Themeasurement environment was 23° C. and 30 RH %. The stylus was moved ina direction perpendicular to the groove direction of engraved lines.

(5-3) Sm Measurement

The Sm values of the first surface and second surface of the obtainedinterlayer film for a laminated glass were measured using a “SurfcorderSE300” available from Kosaka Laboratory Ltd. The measurement wasperformed using a stylus profilometer at a cut-off value of 2.5 mm, astandard length of 2.5 mm, an evaluation length of 12.5 mm, and ameasurement rate of 0.5 mm/s, with a stylus having a tip radius of 2 μmand a tip angle of 60°. The measurement environment was 23° C. and 30 RH%. The stylus was moved in a direction perpendicular to the direction ofgrooves in the shape of engraved lines.

(5-4) Haze Value Measurement

The haze value was measured by the method described in JIS K 7105-1981with a haze and transmittance meter (“HM-150” available from MurakamiColor Research Laboratory). Here the interlayer film for a laminatedglass was set in such a manner that the first surface was on the lightsource side.

Examples 2 to 6

An interlayer film for a laminated glass was obtained in the same manneras in Example 1, except that the conditions for forming recesses in theshape of engraved lines in the second step were changed.

Comparative Example 1

An interlayer film for a laminated glass was obtained in the same manneras in Example 1, except that the grain size of the abrasive materialused in the embossing roll production step 3 in which an embossing rollfor forming the first shape was produced was changed to #800.

Example 7 (1) Preparation of a Resin Composition

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral (acetylgroup content: 1 mol %, butyral group content: 69 mol %, hydroxy groupcontent: 30 mol %). To 100 parts by mass of the polyvinyl butyral wereadded 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO)as a plasticizer, and the mixture was mixed well with a mixing roll togive a resin composition.

(2) Production of an Interlayer Film for a Laminated Glass and Formationof Fine Protrusions and Recesses

According to Production. Example 2, concurrently with the formation ofan interlayer film for a laminated glass, fine protrusions and recesseswere formed on both surfaces of the interlayer film for a laminatedglass.

Specifically, an interlayer film for a laminated glass was formed underthe conditions including the extrusion amount per die width of 440kg/hr·m, the surface temperature of the film immediately after extrusionfrom the die of 200° C., the resin pressure at the die inlet of 80kgf/cm², and the water temperature in the water tank for cooling thefilm of 20° C. to 30° C. in the embossing method in which melt fracturephenomena are controlled, and at the same time, fine protrusions andrecesses were formed on both surfaces of the interlayer film for alaminated glass. In the above step, the distance from the die to thesurface of the cooling water tank was set to 100 mm.

The obtained interlayer film for a laminated glass had a thickness of760 μm. The Rz value measured by the same method as in Example 1 afterformation of the fine protrusions and recesses was 18 μm.

The obtained interlayer film for a laminated glass with fine protrusionsand recesses was subjected to the second step in the same manner as inExample 1, except that the conditions for forming recesses in the shapeof engraved lines were changed. An interlayer film for a laminated glasswas thus obtained.

Examples 8 to 11

An interlayer film for a laminated glass was obtained in the same manneras in Example 7, except that conditions for forming recesses in theshape of engraved lines were changed.

Comparative Example 2

An interlayer film for a laminated glass was obtained in the same manneras in Example 7, except that the distance from the die to the surface ofthe cooling water tank was changed to 200 mm in the embossing method inwhich melt fracture phenomena are controlled.

Examples 12 to 14

An interlayer film for a laminated glass was obtained in the same manneras in Example 1, except that the polyvinyl butyral used had acomposition as shown in Table 2 and the conditions for forming therecesses in the shape of engraved lines in the second step were changed.

Comparative Example 3

An interlayer film for a laminated glass was obtained in the same manneras in Comparative Example 1, except that the polyvinyl butyral used hada composition as shown in Table 2 and the conditions for forming therecesses in the shape of engraved lines in the second step were changed.

Comparative Example 4

An interlayer film for a laminated glass was obtained in the same manneras in Comparative Example 2, except that the polyvinyl butyral used hada composition as shown in Table 2 and the conditions for forming therecesses in the shape of engraved lines were changed.

Evaluation

Formation of a moire pattern in each of the interlayer films for alaminated glass obtained in Examples 1 to 14 and Comparative Examples 1to 4 was evaluated by the following method. Tables 1 and 2 show theresults.

The interlayer film for a laminated glass obtained in each of theexamples and comparative examples was cut to prepare a test sample witha size of 50 mm in length and 50 mm in width. Three pieces of thusobtained test samples were stacked to give a laminate. The laminate wasleft to stand on a 1.5-mm-thick PVB sheet that was placed on an evenglass plate for the purpose of allowing uniform application of a load,with a release paper interposed between the laminate and the PVB sheet.Here, the release paper was prepared by coating base paper with siliconeas releasing treatment. Then, a glass plate of 6-kg weight was placed onthe laminate with a release paper interposed therebetween. The releasepaper was prepared by coating base paper with silicone as releasingtreatment. After standing at 23° C. for 72 hours, the interlayer filmfor a laminated glass placed in the middle of the laminate was taken outand subjected to a moire test within three minutes after being takenout.

The moire test was performed as follows. The interlayer film for alaminated glass was set at a position of 1 m from a lamp, and 20evaluators visually observed the interlayer film from a position on theopposite side of the lamp across the interlayer film and obliquely at anangle of 45°. The number of people who noticed a moire pattern and thenumber of people who felt that the moire pattern was unpleasant werecounted.

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 Compositon Polyvinyl Average degreeof — 1700 1700 1700 1700 1700 1700 1700 1700 1700 1700 of interlayerbutyral resin polymerization of PVA film Degree of butyralization mol %69 69 69 69 69 69 69 69 69 69 Degree of acetylation mol % 1 1 1 1 1 1 11 1 1 Hydroxy group content mol % 30 30 30 30 30 30 30 30 30 30 AmountParts by 100 100 100 100 100 100 100 100 100 100 mass Plasticizer Type —3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 40 40 40 40 4040 40 40 40 40 mass Method of Melt fracture Distance from die to mm — —— — — — 100 100 100 100 providing fine method surface of water tankprotrusions Embossing Abrasive material used Mesh #320 #320 #320 #320#320 #320 — — — — and recesses roll method in embossing roll productionstep 3 Protrusions First surface Glossiness % 4.2 4.9 8.0 4.9 6.5 15.410.0 10.5 3.9 7.0 and recesses Rz μm 44 35 25 35 37 50 35 35 45 49 onthe surface Sm μm 200 200 195 200 260 395 203 201 201 220 SecondGlossiness % 4 4.5 8 4.6 5.4 14.2 11.2 11.9 3.5 7 surface Rz μm 42 36 2736 38 45 34 34 43 45 Sm μm 185 185 186 185 250 390 201 201 201 215Intersection angle of recesses ° 20 20 20 90 90 20 90 20 20 45 Hazevalue % 84.4 82.9 80.0 82.8 82.5 72.0 83.2 83.3 86.2 83.3 EvaluationMoire test Number of people who noticed 13 10 8 9 7 6 14 15 17 8 moirepattern Number of people who felt that 2 0 0 0 0 0 2 3 4 0 moire patternwas unpleasant

TABLE 2 Example Comparative Example 11 12 13 14 1 2 3 4 CompositonPolyvinyl Average degree of — 1700 1700 1700 1700 1700 1700 1700 1700 ofinterlayer butyral resin polymerization of PVA film Degree ofbutyralization mol % 69 69 69.9 68.4 69 69 69.9 68.4 Degree ofacetylation mol % 1 1 1.1 0.7 1 1 1.1 0.7 Hydroxy group content mol % 3030 29 30.9 30 30 29 30.9 Amount Parts by 100 100 100 100 100 100 100 100mass Plasticizer Type — 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by40 40 40 40 40 40 40 40 mass Method of Melt fracture Distance from dieto mm 100 — — — — 200 — 200 providing fine method surface of water tankprotrusions Embossing Abrasive material used Mesh — #320 #320 #320 #800— #800 — and recesses roll method in embossing roll production step 3Protrusions First surface Glossiness % 13.9 3.5 4.4 5.0 3.0 2.9 2.8 2.9and recesses Rz μm 43 48 42 35 50 53 52 51 on the surface Sm μm 350 190199 195 200 195 200 195 Second Glossiness % 15 3.4 4.4 4.6 3 2.9 2.5 2.9surface Rz μm 50 48 40 35 52 51 54 51 Sm μm 350 175 195 180 198 203 195186 Intersection angle of recesses ° 20 20 20 20 20 20 20 20 Haze value% 79.0 86.5 83.0 82.5 87.8 88.1 88.0 87.9 Evaluation Moire test Numberof people who noticed 2 20 13 9 20 20 20 20 moire pattern Number ofpeople who felt that 0 8 1 0 18 17 18 14 moire pattern was unpleasant

Example 15 Preparation of a Resin Composition for a Protective Layer

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral (acetylgroup content: 1 mol %, butyral group content: 69 mol %, hydroxy groupcontent: 30 mol %). To 100 parts by mass of the polyvinyl butyral wasadded 36 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO)as a plasticizer, and the mixture was sufficiently kneaded with a mixingroll to prepare a resin composition for a protective layer.

(Preparation of a Resin Composition for an Intermediate Layer)

Polyvinyl alcohol having an average degree of polymerization of 3,000was acetalized with n-butyraldehyde to give polyvinyl butyral (acetylgroup content: 12.5 mol %, butyral group content: 64.2 mol %, hydroxygroup content: 23.3 mol %). To 100 parts by mass of the polyvinylbutyral was added 76.5 parts by mass of triethyleneglycol-di-2-ethylhexanoate (3GO) as a plasticizer, and the mixture wassufficiently kneaded with a mixing roll to prepare a resin compositionfor an intermediate layer.

Production of an Interlayer Film for a Laminated Glass

The obtained resin composition for an intermediate layer and resincomposition for a protective layer were co-extruded using a co-extruderto form an interlayer film for a laminated glass having a triple layerstructure including a first protective layer made of the resincomposition for a protective layer, an intermediate layer made of theresin composition for an intermediate layer, and a second protectivelayer made of the resin composition for a protective layer, stacked inthe stated order. The extrusion conditions were set such that the firstand second protective layers each had a thickness of 350 μm and theintermediate layer had a thickness of 100 μm in an interlayer film for alaminated glass to be obtained after formation of protrusions andrecesses.

Then, the protrusions and recesses were formed on the interlayer filmfor a laminated glass in the same manner as in Example 1, except thatthe type of the blasting material used in the embossing roll productionstep 3 in which the embossing roll for forming the first shape wasproduced was changed and the pressure upon transferring the pattern ofprotrusions and recesses was adjusted so that the desired Rz value wasachieved. The protrusions and recesses on the both surfaces weremeasured.

Example 16 Production of an Interlayer Film for a Laminated Glass andFormation of Fine Protrusions and Recesses

A resin composition for an intermediate layer and a resin compositionfor a protective layer were obtained in the same manner as in Example15. The obtained resin composition for, intermediates layer and resincomposition for a protective layer were coextruded using a co-extruderto form an interlayer film for a laminated glass having a triple layerstructure including a first protective layer made of the resincomposition for a protective layer, an intermediate layer made of theresin composition for an intermediate layer, and a second protectivelayer made of the resin composition for a protective layer, stacked inthe stated order. In that process, according to Production Example 2,the first shape was provided concurrently with the formation of theinterlayer film for a laminated glass. Specifically, in the embossingmethod in which melt fracture phenomena are controlled, an interlayerfilm for a laminated glass was formed under the conditions including theextrusion amount per width of the die of 440 kg/hr·m, the surfacetemperature of the film immediately after extrusion from the die of 200°C., the resin pressure at the die inlet of 80 kgf/cm², and the watertemperature in the water tank for cooling the film of 20° C. to 30° C.At the same time, fine protrusions and recesses were formed on bothsurfaces of the interlayer film for a laminated glass. In the abovestep, the distance from the die to the surface of the cooling water tankwas set to 100 mm. The obtained interlayer film for a laminated glasswith fine protrusions and recesses was subjected to the second step inthe same manner as in Example 1, except that the conditions for formingthe recesses in the shape of engraved lines were changed. An interlayerfilm for a laminated glass was thus obtained. The first protective layerand second protective layer of the obtained interlayer film for alaminated glass each had a thickness of 350 μm and the intermediatelayer had a thickness of 100 μm.

Examples 17 to 21

An interlayer film for a laminated glass was produced in the same manneras in Example 15, except that the polyvinyl butyral used had acomposition as shown in Table 3 or 4 and that the type of the blastingmaterial used in the embossing roll production step 3 in which anembossing roll for forming the first shape was produced and the pressureupon transferring of the pattern of protrusions and recesses wereadjusted so that the desired Rz value was achieved. The protrusions andrecesses on each surface of the obtained interlayer film for a laminatedglass were measured.

Comparative Example 5

An interlayer film for a laminated glass was obtained in the same manneras in Example 15, except that the grain size of the abrasive materialused in the embossing roll production step 3 in which an embossing rollfor forming the first shape was produced was changed to #800.

Comparative Example 6

An interlayer film for a laminated glass was obtained in the same manneras in Example 16, except that the distance from the die to the surfaceof the cooling water tank in the embossing method in which melt fracturephenomena are controlled was changed to 200 mm.

Evaluation

Formation of a moire pattern in each of the interlayer films for alaminated glass obtained in Examples 15 to 21 and Comparative Examples 5and 6 was evaluated by the same method as described above. Tables 3 and4 show the results.

TABLE 3 Example 15 16 17 18 19 First and Polyvinyl Average degree of —1700 1700 1700 1700 1700 second butyral polymerization of PVA protectiveresin Degree of butyralization mol % 69 69 69 69.9 69.9 layers Degree ofacetylation mol % 1 1 1 1.1 1.1 Hydroxy group content mol % 30 30 30 2929 Amount Parts by 100 100 100 100 100 mass Plasticizer Type — 3GO 3GO3GO 3GO 3GO Amount Parts by 36 36 36 39 39 mass Structure Thickness μm350 350 350 360 350 Intermediate Polyvinyl Average degree of — 3000 30001700 2300 3000 layer butyral polymerization of PVA resin Degree ofbutyralization mol % 64.2 64.2 64.2 77.8 77.8 Degree of acetylation mol% 12.5 12.5 12.5 1.5 1.5 Hydroxy group content mol % 23.3 23.3 23.3 20.720.7 Amount Parts by 100 100 100 100 100 mass Plasticizer Type — 3GO 3GO3GO 3GO 3GO Amount Parts by 76.5 76.5 76.5 79 79 mass StructureThickness μm 100 100 100 100 100 Whole Structure Structure — First FirstFirst First First interlayer protective protective protective protectiveprotective film layer/ layer/ layer/ layer/ layer/ intermediateintermediate intermediate intermediate intermediate layer/secondlayer/second layer/second layer/second layer/second protectiveprotective protective protective protective layer layer layer layerlayer Thickness μm 800 800 800 800 800 Method of Melt-fracture Distancefrom die to mm — 100 — — — providing fine method surface of water tankprotrusions Embossing Abrasive material in Mesh #320 — #320 #320 #320and recesses roll method embossing roll production step 3 ProtrusionsFirst Glossiness % 4.2 9.8 4.1 4,5 4.3 and recesses surface Rz μm 43 344.2 42 43 on surface Sm μm 200 200 201 204 202 Second Glossiness % 4.310.6 4.4 4.5 4.4 surface Rz μm 40 37 41 42 42 Sm μm 195 198 194 204 200Intersection angle of recesses ° 20 90 20 20 20 Haze value % 84.6 83.484.5 83.5 83.4 Evaluation Moire test Number of people who noticed 14 1614 13 13 moire pattern Number of people who felt that 2 2 2 1 1 moirepattern was unpleasant

TABLE 4 Example Comparative Example 20 21 5 6 First and PolyvinylAverage degree of — 1700 1700 1700 1700 second butyral polymerization ofPVA protective resin Degree of butyralization mol % 68.5 68.5 69 69layers Degree of acetylation mol % 0.5 0.5 1 1 Hydroxy group content mol% 31 31 30 30 Amount Parts by 100 100 100 100 mass Plasticizer Type —3GO 3GO 3GO 3GO Amount Parts by 36 36 36 36 mass Structure Thickness μm350 350 350 350 Intermediate Polyvinyl Average degree of — 3000 17003000 3000 layer butyral polymerization of PVA 67 67 64.2 64.2 resinDegree of butyralization mol % Degree of acetylation mol % 8 8 12.5 12.5Hydroxy group content mol % 25 25 23.3 23.3 Amount Parts by 100 100 100100 mass Plasticizer Type — 3GO 3GO 3GO 3GO Amount Parts by 75 75 76.576.5 mass Structure Thickness μm 100 100 100 100 Whole StructureStructure — First First First First interlayer protective protectiveprotective protective film layer/ layer/ layer/ layer/ intermediateintermediate intermediate intermediate layer/second layer/secondlayer/second layer/second protective protective protective protectivelayer layer layer layer Thickness μm 800 800 800 800 Method ofMelt-fracture Distance from die to mm — — — 200 providing fine methodsurface of water tank protrusions Embossing Abrasive material in Mesh#320 #320 #320 #800 and recesses roll method embossing roll productionstep 3 Protrusions First Glossiness % 5.5 5.5 3.0 2.9 and recessessurface Rz μm 33 34 50 53 on surface Sm μm 190 188 200 195 SecondGlossiness % 5.3 5.2 2.9 2.9 surface Rz μm 35 34 51 53 Sm μm 185 180 198203 Intersection angle of recesses ° 20 20 20 20 Haze value % 82.5 82.587.5 88.1 Evaluation Moire test Number of people who noticed 8 8 20 20moire pattern Number of people who felt that 0 0 16 18 moire pattern wasunpleasant

INDUSTRIAL APPLICABILITY

The present invention can provide an interlayer film for a laminatedglass having recesses in the shape of engraved lines on both surfaces toexhibit excellent deaeration properties in production of a laminatedglass and suppressing formation of a moire pattern when unwound from arolled body thereof. The present invention can also provide a laminatedglass including the interlayer film for a laminated glass, a method forproducing an embossing roll suitably used for production of theinterlayer film for a laminated glass, and a method for producing theinterlayer film for a laminated glass.

REFERENCE SIGNS LIST

-   1: Arbitrarily selected one recess-   2: Recess adjacent to the arbitrarily selected one recess-   3: Recess adjacent to the arbitrarily selected one recess-   A: Interval between recess 1 and recess 2-   B: Interval between recess 1 and recess 3-   10: Interlayer film for a laminated glass-   11: Recess having a groove shape with a continuous bottom on first    surface-   12: Recess having a groove shape with a continuous bottom on second    surface-   20: Protrusions and recesses on first surface or second surface-   21: Recess having a groove shape with a continuous bottom-   22: protrusion

The invention claimed is:
 1. An interlayer film for a laminated glass,having recesses on both surfaces, the recesses each having a grooveshape with a continuous bottom and being regularly adjacent and parallelto each other, the interlayer film having a glossiness on a surface withthe recesses measured in conformity with JIS Z 8741-1997 of higher than3% and a haze value measured in conformity with JIS K 7105-1981 of 87%or lower, wherein an interval Sm between the recesses each having agroove shape with a continuous bottom is 350 μm or less, and wherein theinterlayer film includes a resin layer comprising polyvinyl acetal and aplasticizer.
 2. A laminated glass comprising: a pair of glass plates;and the interlayer film for a laminated glass according to claim 1interposed between the pair of glass plates.
 3. A method for producingthe interlayer film for a laminated glass according to claim 1, saidmethod comprising providing recesses on at least one surface of aninterlayer film for a laminated glass by an embossing roll method usingan embossing roll produced by a method comprising: an embossing rollproduction step 1 of forming protrusions and recesses on a metal roll byblasting with an abrasive material; an embossing roll production step 2of grinding a protion of each protrusion on the metal roll provided withthe protrusions and recesses into a flat surface portion; and anembossing roll production step 3 of forming protrusions and recesses byblasting with an abrasive material finer than the abrasive material usedin the embossing roll production step
 1. 4. A method for producing theinterlayer film for a laminated glass according to claim 1, the methodbeing intended to form recesses on at least one surface of an interlayerfilm for a laminated glass by an embossing method in which melt fracturephenomena are controlled, the method comprising the step of: extruding aresin composition from a die to form an interlayer film for a laminatedglass; and cooling the extruded interlayer film for a laminated glass ina cooling water tank, a distance between the die and the cooling watertank being adjusted to 250 mm or shorter in the cooling.
 5. A method forproducing the interlayer film for a laminated glass according to claim1, said method comprising providing recesses on at least one surface ofan interlayer film for a laminated glass by an embossing roll methodusing an embossing roll produced by a method comprising: an embossingroll production step 1 of forming protrusions and recesses on a metalroll by blasting with an abrasive material; an embossing roll productionstep 2 of grinding a portion of each protrusion on the metal rollprovided with the protrusions and recesses into a flat surface portion;and an embossing rill production step 3 of forming protrusions andrecesses by blasting with an abrasive material finer than the abrasivematerial used in the embossing roll production step 1, wherein theabrasive material used in the embossing roll production step 3 has agrain diameter at a cumulative height of 3% in conformity with JIS R6001(1998) of 11 μm or more.
 6. The interlayer film for a laminated glassaccording to claim 1, having a haze value measured in conformity withJIS K 7105-1981 of 72% to 87%.